Selection of first interruption pulse for synchronization of vertical sweep generators



Aug. 22 1950 KUPERUS 2,519,911 SELECTION OF FIRST INTERRUPTION PULSES FOR SYNCHRONIZATION 0F VERTICAL SWEEP GENERATORS Filed July 15, 1947 2 Sheets-Sheet 1 INVENTOR JAN. KUPERUS AGENT 2, 1950 J. KUPERUS SELECTION OF FIRST INTERRUPTION PULSES FOR SYNCHRONIZATION OF VERTICAL SWEEP GENERATORS 2 Sheets-Sheet 2 Filed July 15, 1947 DveflZZn' JAN KUPf/il/S 3 v AGE/VT Patented Aug. 22, 1950 SELECTION OF FIRST INTERRUPTION PULSE FOR SYNCHRONIZATION OF VERTICAL SWEEP GENERATORS Jan Kuperus, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., trustee Application July 15, 1947, Serial No. 761,050 In the Netherlands July 15, 1946 6 Claims.

1 My copending U. S. patent application, Serial No. 727,468, filed February 8, 1947, now Patent No. 2,493,353, issued January 3, 1950, describes a circuit-arrangement for synchronizing the image time-base generator in a receiver for stationary or moving images. In this arrangement there is received, together with the image signal, a mixture of line synchronizing pulses and image synchronizing pulses interrupted by interrupting impulses. This mixture is supplied, after the image signal is cut off, to an integrating network, the output voltage of which is fed to a control electrode of a discharge system and the signal voltage being supplied, if necessary after the image signal is cut off, to the same or to another control electrode of this system, the output electrode of the discharge system having taken from it a voltage, with the aid of which the image is synchronized.

The above described circuit-arrangement has the disadvantage that the selected signal for the synchronisation of the image time-base generator is built up from a series of impulses which are derived from the series of interrupting impulses. It is, in general, desirable that for synchronisation purposes only one interrupting impulse should be used, since a plurality of impulses may give rise to interference. Thus, for example, if the image time-base generator comprises a gasfilled discharge tube, it may be possible for this tube to be opened at all impulses of the series after the first impulse of this series has already brought about the discharge of the condenser included in the sawtooth generator. The beginning of the image sawtooth voltage is, in this case, governed by the last impulse of the series, which for example in the case of interlaced reproduction, may lead to irregularities.

The principal object of the invention is to provide a circuit arrangement in which these disadvantages are obviated.

It exhibits the feature that a voltage derived from a saw-tooth voltage produced by the image time-base generator is fed to a control electrode of the discharge system in such manner that only the first interrupting impulse of each image synchronizing impulse occurs in the output circuit of this system.

In order that the invention may be more clearly understood and readily carried into eflect, it will now be explained more fully with reference to the accompanying drawing in which:

Figure 1 is a schematic diagram of a circuit arrangement according to the invention,

- i Fig. 2 are graphs illustrating the wave form of advantages.

the voltages at various portions of the circuit arrangement according to the invention, and

Fig. 3 is a schematic diagram of a circuit arrangement in accordance with another embodiment of the invention.

Fig. 1 shows, partly in block diagram, one embodiment of the circuit-arrangement according to the invention. There is fed to a control electrode of a discharge tube 2 a voltage V1 and, in addition, a fixed bias voltage. Voltage V1, as a function of time, is illustrated in Fig. 2.

The voltage V1 is formed from the incoming television signal by cutting off the image signal and, consequently, merely consists of a mixture of synchronizing impulses, viz. line synchronizing pulses a, image synchronizing pulses b and interrupting impulses c. In the present television transmitting systems these interrupting impulses have double the frequency of the line synchronizing pulses.

Fig. 2 illustrates two image synchronizing impulses, one of which is associated with the even image raster, the other with the odd image raster.

Voltage V1 has derived from it, with the aid of a phase-reversing device 3 and an integrating network 4, a voltage V2, which, so far as it exceeds a threshold voltage which has also been applied and the value of which is shown in Fig. 2 by a dotted line 01, is fed to a control electrode 5 of the discharge tube. Due to the said applied voltage, the discharge tube 2 will conduct only for the time periods ii to t2 or is to 754 respectively, so that across the anode resistance 6 is set up a voltage V3 in which only the interrupting impulses occur. This voltage is converted, with the aid of a differentiating network 1, into a voltage having a shape V4. Voltage V4 is fed to the image saw-tooth generator 8. If this generator is responsive to :positive impulses, synchronisation consequently occurs in principle on the rear front of the first interrupting impulse. However, it may be seen from Fig. 2 that impulses of the voltage V4 are of the same value for each interrupting impulse, which may be responsible for the aforesaid dis- In order to obviate these disadvantages, there is derived from the image time-base generator 8 a voltage having a shape V5 which is supplied to the control electrode I through the intermediary of a resistance l l and via a network consisting of a condenser 9 and a resistance It).

The voltage set up across the resistance ll! has 'a shape Vs, the maximum voltage occurring being consequently reached more gradually, i. e. with a smallerslope than in the case of voltage V5. On the control electrode I there is now set up a total voltage of the shape V: which is substantially equal to the sum of the voltages V1 and V6. Owing to the smaller slope of the variation characteristic curve of voltage V6 in the neighbourhood of the maximum value, the shape of the first interrupting impulse is not deformed to any appreciable extent. This is in contradistinction to the second interrupting impulse, for example, which falls Within the fly-back time of the timebase generator and is thus superimposed on a very steep portion of the curve. When the first interrupting impulse occurs, voltage V2 exceeds the threshold value and thevoltage onthe con.-

trol electrode i is sufiiciently high so that the. tube is alive and the first interrupting impulseoccurs in the output circuit, When the second and subsequent interrupting pulses occur, the voltage V2 still exceeds the threshold Value, it is true, but the voltage on the control electrode I has decreased to an extent such that the tube does not conduct and hencev these impulses are 1 allowed to-pass. as; a result, .a voltage haw in a. shape Va is. set. up across.- the anode resistance G. This voltage is fed via the differentiating network I to thein'iagesaw-tooth gen.- era tor whichiis, consequently, synchronized with theaidof thefirst interrupting impulse, without thesubsequent. interrupting impulses being capable of actinguponthe image time-base genenator.-

Fig. 3shows .af-urther embodiment of the circuit-arrangement according to the invention.

A. grid l2. of the hexode part of the discharge system of a. tube l3 has fed to it, via a bias voltage supply battery 5, a voltage theshape of which is similar tothat of V1 illustrated in Fig. 2, but which is of opposite polarity. This voltage .is reversed in sensewiththeaid of the hexode partof the discharge system'and integrated, because anode [5 is practically earthedthrough condenser l6, resistance if being small, so that the-voltageset up across it is negligible relatively-to that set up across condenser H5. The integrated voltage issupplied through a condenser wand-a resistance! B-to the anode 20 of the-triode part of the discharge system which anode operates as a control electrode The integrated voltage is transferred at thesame time b-y-I-neans of: the coupling condenser 2| and resistance 22 to the output circuit, ifthe triode'pa'rt is-not conductive. The control-grid 23 is connected through resistances 24 and: ll 1 to the bias voltage battery 25. The resistance I forms part of" the anode circuit. of the. hexode-part and not shunted'by a condenser, so that there is set up 7 at the control-grid a voltage .of the shape V1. As soon asthe grid voltage becomes negative, under. the influence of voltage V1, to an extent such that the triode part is no longer conductive, the voltage V2 set up on the anode istransmitted to the output, the output is short-circuited. Cone sequently, a voltage of the shape Vaoccurs across the-output circuit. Thi volta e may bored to one of the grid or a. gasfilled discharge tube which forms part of an image sawtooth generator known. In this.case synchronisationocpurs on the front flanks of the interrupting impulses,

In order to eliminate any interference produced by. the further interrupting impulses, part of theanodevoltage of tube 28, in this. case the final pentode of the image time-base generator, is supplied through a differentiating network consisting of a condenser 21' and a resistance 26"to the control-grid of the triode part ofthe tube I3, said part being of the sameshape as the voltage V6, but of opposite polarity, The voltage on this control-grid will, consequently, become positive directly upon the occurrence of the first interrupting impulse at which synchronisation is eifected, so that the output circuit short-circuited-by thetriode part. and the, subsequent interrupting impulses are suppressed.

What I claim is:

1. A synchronizing circuit arrangement for a television receiver responsive to signals comprising line synchronizing pulses and image synchronizing pulses comprising a plurality of interruption impulses occurring within the period of Said imagesynchronizing pulses and appearing in fixed timerelationship with respect to said line synchronizing pulses, comprising a normally closed transmission path, means to apply said signals to said transmission path, means to reverse thephase of said signals, means to integrate said reversed phase signals to produce a first control; voltage, means .to apply said. firstcOntrol voltagetosaid, transmission path .to. open same thereby. to transmit said. interruption impulses only, means; .to- .difierentiate said. transmitted. interruption impulses, means toapplysaid diner.- .entiated: interruption impulses .to an. image saw.- tooth generator toaproduce .a sawtooth. voltage, means to derive a. secpndcontrol voltage from said sawtooth, voltage, .and:means to apply said second controlivoltage toisaid transmission path to transmitonIy the first of. said interruption impulses 2. Aosynohronizing-lcircuit arrangement. for a television receiver responsiveto signals comprising line synchronizing. pulsesand image synchronizing pulses comprising a. plurality. ofin terruption impulses occurring within the period of: said imagesynchronizing pulses and 7 appearing in fixed time relationship with respect to'said line synchronizing pulses, comprising anormally closed transmission-path, meansto apply said signals tosa-id transmission path, means to v reverse-the phase of said:signals, means to integrate said-r-eversed phase signals to-produce a first control voltage, means toiappl-y saidfirst control voltage to said transmission'pat-hto open same thereby to.transmit saickinterruption impulses only, meansto differentiate saidtransmitted interruption irnpulses, means to apply said differentiatedinterruption impulses to =-an image saw-tooth generator to produce-a-sawtooth voltage, means to differentiate said saw-tooth voltage to derivea second controlvoltage from said sawtoothgenerator,- and means'to apply said second control voltage-to saidtransmission path to transmit-on-lythe first; of said interruption'impulses.

3; A synchronizing circuit arrangement for a television receiver. responsive-t0 signalsccomprising; line synchronizing. pulses and. image synchronizing pulseshcomprising: a plurality of: interruption impulses occurring within 1 the period of said image-synchronizing pulses and appearing in fixedtime relationshippwith respecttto said line Synchronizinapulses, comprising .an electron -dis- .charge'tube having ahcathode afirst control grid,- asecondcontrol gridand an anode; .means to apply. .saidisignals .to .the first control. grid of said tube, means to reverse the phasetofsaidsignals, means to integratesaid reversed phase signals- .to' produce .a: firsttcontrol 2 voltage; means to apply.- said: first control voltage to thesecond control grid :ofssaidtube thereby to produce said interruption impulses: only. at; the anode 1 of said tube, meansto nififerentiaiesaid-interruption impulses; means-to :flaDDlYvsSil-iik difierentiatedinterruption impulses to an image sawtooth generator to produce a sawtooth voltage, means to differentiate said sawtooth voltage to derive a second control voltage from said sawtooth generator, and means to apply said second control voltage to the first control grid of said tube to produce only the first or said interruption impulses at the anode of said tube.

4. A synchronizing circuit arrangement for a television receiver responsive to signals comprising line synchronizing pulses and image synchronizing pulses comprising a plurality of interruption impulses occurring within the period of said image synchronizing pulses and appearing in fixed time relationship with respect to said line synchronizing pulses, comprising a first electron discharge system having a cathode, a control grid and an anode, a second electron discharge systern having a cathode, a control grid coupled to the control grid of said first electron discharge system and an anode, means to apply said signals to the control grids of said first and said second electron discharge systems, means coupled to the anode of said first electron discharge system to produce a signal voltage reversed in phase with respect to said signals, means coupling the anode of said first electron discharge system to the anode of said second electron discharge system, means to integrate said reversed phase signal voltage to produce a first control voltage, means to apply said first control voltage to the control grids of said first and said second electron discharge systems t'herehy to produce said interruption impulses only at the anode of said second discharge system, means to differentiate said interruption impulses, means to apply said differ entiated interruption impulses to an image sawtooth generator to produce sawtooth voltage, means to difierentiate said sawtooth voltage to derive a second control voltage from said sawtooth generator, and means to apply said second control voltage to the control grids of said first and said second electron discharge systems to produce only the first of said interruption impulses at the anode of said second electron discharge system.

5. A synchronizing circuit arrangement for a television receiver responsive to signals comprising line synchronizing pulses and image synchronizing pulses comprising a plurality of interruption impulses occurring within the period of said image synchronizing pulses and appearing in fixed time relationship with respect to said line synchronizing pulses, comprising an electron discharge tube having a first electron discharge system having a first output electrode, a second electron discharge system having a second output electrode, electron emitting means and input electrode means for said first and said second electron discharge systems, means to apply said signals to said input electrode means, means coupling the output electrodes of said electron discharge systems, means coupled to said first output electrode to produce a potential reversed in phase and proport' nal to said signals, means to integrate potential to produce a first control voltage, means to apply said first control voltage to said input electrode to produce an output potential on said second output electrode, means to differentiate said output potential to produce a second control voltage, a sawtooth voltage generator, means to apply said second control voltage to said sawtooth generator to produce therefrom sawtooth output voltage, means to differentiate said sawtooth output voltage to produce third control voltage, and means to apply said third control voltage to said input electrode means to produce only the first of said interruption impulses on said second output electrode.

6. A synchronizing circuit arrangement for a television receiver responsive to signals comprising line synchronizing pulses and image synchronizing pulses comp 'sing a plurality of interruption impulses occurring within the period of said image synchronizing pulses and appearing in fixed time relationship with respect to said line synchronizing pulses, comprising a first electron discharge system having a first output electrode and screen electrodes, a second electron discharge system having a second output electrode, electron emitting means for said first and said second electron discharge systems, means to apply said signals to said input electrode means, capacitive means couplin said first and said second output electrode, an integrating circuit coupled to said first output electrode and to said input electrode means, a first differentiating circuit coupled to said second output electrode, a sawtooth signal generator having an input circuit coupled to said first differentiating circuit and an output circuit, a second difierentiating circuit coupled to the output circuit of said sawtooth signal generator and to said input electrode means thereby to apply only the first of said interruption impulses to the input of said sawtooth signal generator.

JAN KUPERUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,242,633 Toulon May 20, 1941 2,358,545 Wendt Sept, 15, 1944 FOREIGN PATENTS Number Country Date 847,675 France Oct. 13, 1939 

